Electrical conversion of transient vector signals for recorder application



April 4, 1967 B. BARBER ETAL.

ELECTRICAL CONVERSION OF TRANSIENT VECTOR SIGNALS FOR RECORDERAPPLICATION 4 Sheets-Sheet l Filed Oct. 28, 1963 S WS E@ m@ vw n m MMANf. EMB 5M April 4, 1967 B. BARBER ETAL 3,312,932

ELECTRICAL CONVERSION OF TRANSIENT VECTOR SIGNALS FOR RECORDERAPPLICATION Filed Oct, 28, 1963 4 Sheets-Sheet 2 Z E EO CROSS/NG D/RECr/ofv al 6 WEEP MASTER 44 CL DCK 40 Il Il FPO MZ/VD GAT GA 75 COUNTER[if ,4 FPO/W CAPE/E7? M OSC/LATO? fO.

No 770A/ 0F /GHT 55A M -J ATTORNEYS A101114, 1967 B. BARBER ETAL3,312,932

I ELECTRICAL CONVERSION OF TRANSENT VECTOR SIGNALS FOR RECORDERAPPLICATION Filed Oct. 28, 1965 4 Sheets-Sheet 5 /VEDLES PHTO SENS/T/l/EQ TACK D/e-cr/QNAL SOA/A@ X @fc5/V5@ Laos/V5 CHAQGES GEOGRAPH/CAL R407*INVBNToRs BEA/0 BA/QE/Q KENNETH W. GROSS April 4, 1967 Filed OCT.. 28,1965 B. BARBER ETAL.

ELECTRICAL CONVERSION OF TRANSIENT VECTOR SIGNALS FOR RECORDERAPPLICATION 4 sheets-sheet 4 United States vPatent tifice 3,3 lZSZPatented Apr. 4, 1967 Ware Filed oct. 2s, 1963, ser. No. 319,598 zclaims. (ci. 340-6) This invention relates to a system for displaying orrecording electrical signals and in particular the instantaneousdirection angle of an electrical vector having momentarycharacteristics.

There are presently known processing circuits designed to provide X andY voltages which are components determined by the magnitude anddirection of a signal vector. The present invention provides a methodfor displaying or recording in some form this electrical signal vector.The vector may be shown as by an oscilloscope or as a printed record.

In addition to displaying a single electrical signal, the oscilloscopeor recorder, according to the invention, is enabled to correlate two ormore signals by determining their time difference and their angledilerence even though the signals do not occur simultaneously; also, therecording system can correlate direction angles of electrical signalswith other -phenomena occuring at the same time in the system. Thesystem is operative whether or not the direction angle of the displayedsignal varies during observation and is not limited by the time durationof the vector signal which describes the direction angle.

One object of the invention is to provide a system for recording thedirection angle of a signal which exists only momentarily.

Another object of the invention is to provide a signal recorder which isenabled to correlate two or more electrical Signals both in terms oftime and their direction angle.

Other objects and advantages of the invention may be appreciated onreading the following description which is taken in conjunction with theaccompanying drawings, in which:

FIG. l is a block diagram of the recording apparatus arranged accordingto the invention;

FIG. 2 illustrates the signals produced in the recording system;

FIG. 3 is an illustration of a photoelectric printer for recordingdirection angle signals;

FIG. 4 illustrates a count and print out system for recording directionangle signals;

FIG. 5 illustrates an electric needle type print out for a directionangle recording system;

FIG. 6 is a target track plot;

FIG. 7 is a bearing time recorder plot effected without explosivecharges;

FIG. 8 is a bearing time recorder plot effected with the use ofexplosive charges.

This invention is designed to operate with a .signal data processingcircuit that provides an X and Y voltage proportional to the directionof a signal vector. The characteristic of the signal is that it may bemomentary and ileeting. In a general sense, the direction angle of theelectrical signal, whose X and Y component voltages are placed in thepresent system, is derived according to the following function:

(l) X cos (ctH-Y sin (wt) The value of the function reaches a maximum atits angular position wt corresponding to the direction angle of thesignal vector. This may be demonstrated by taking the derivative of thefunction and equating the derivative to zero to find the relationbetween the variables wt, X and Y of the function at its maximum Value.

Thus t [X cos (wt) Y sin (wt)]= (-X sin wtO-I-Y cos mio) =0 and,therefore,

= tan @to where t0 is taken relative to the carrier oscillator and w isthe radian frequency of the carrier oscillator. The input mechanism incontrol of the display determines when such maximum occurs and actuatesthe display accordingly.

Referring to FIG. l, the signal Y sin (wt) is generated by applying acarrier signal sin (wt) from oscillator l0 to modulator 12 whose inputis the Y component. The signal X cos (wt) is generated by applying aphase shifted carrier through phase shifter 14 to modulator 16 n whoseinput is the X component.

The sum Y sin (wt) |X cos (wt) computed by summing amplii'ier 18 is fedto a 90 phase shifter 20 and is then fed to a zero crossing detector 22which produces a pulse whenever the signal goes through a zero point.The detector is used because the Zero point is defined more sharply thana maximum point. See FIG. 2b.

To prevent the system noise from generating erroneous zero crossingpulses during the time when no vector signal is present, the sum X COS(wI)-l-Y sin (wt) is also fed to a signal threshold trigger 24 whichgives no output for system noise but will give a pulse output when ispresent and positive. Both the zero crossing circuit and thresholdcircuit are fed to an AND gate 26 whichy gives an output only when bothsignals are .present at the same time.

A linear sweep generator 28 which is synchronized to the carrieroscillator 10 is -applied by channel A to the vertical input plates of adual beam oscilloscope tube 30. The linear sweep will be del-ined as thedirection sweep and the width corresponds to one cycle of carriersignal. See FIG. 2a and FIG. 2d. The slope of the sweep signal is chosensuch that a complete sweep moves the electron beam across 360 markingson the face of the tube. The beam intensity is turned down so that onlythe signal coming from the AND gate 26 applied to Z axis of scope willilluminate a point on the scope. Thus, the pulse which is generated atthe time when is maximum illuminates a point on the scope correspondingto the direction angle determined by the X and Y components.

It may be desired to measure the difference in time between two or moredirection angles. To that end, there is provided threshold detector 32which detects pulses passed by the AND gate 26 representing the firstdirection angle. Linear time sweep generator 34 is actuated by thedetector 32 to apply a time sweep on channel A to the horizontal inputplates of the oscilloscope tube 30. To measure the time between theexistence of two or more direction angles, the time sweep is initiatedby the tirst direction angle signal and the sweep is used to measure thetime of appearance for the next succeeding signal. This is achieved dueto the fact that the first signal is employed to initiate movement ofthe horizontal deflection plates by means of the sweep generator 34. Asweep cycle is therefore completed regardless of the presence of othersignals. Once the rst signal has disappeared there will be noillumination until the second signal yappears on the Z axis `at whichpoint the displacement of the horizontal beam can be perceived and thisdisplacement will therefore be a measure of the time difference betweenthe two signals.

The time sweep generated by unit 34 is also placed on channel B andapplied to the horizontal input plates in control of the second beam ofthe sweep oscillator 30. A signal representing some event in the systemmay then be placed on channel B to be applied to the vertical inputplates for the second beam. Such an event may be the instant of timewhen a torpedo is red to destroy a target the time indicating signalbeing placed on channel B as by radio relay signal. The time of theevent with reference to the time of the direction angle signal whichinitiated the time sweep in channel B can then be measured by the timesweep developed in the scope by the horizontal plates.

For recording purposes the pulse iinom the AND gate 26 may be used tocomm-and Ia print out onto light sensitive paper. As shown in FIG. 3, laphotoelectric scanning yhead 34 is disposed over photosensitive paper G6which is shielded from other light sources not shown. A direction sweepfnom generator 2@ moves the light sour-ce across the width of the paper.The light source in the scanning head is normally off but on gate pulsecommand will produce a beam for print yont onto the light sensitivepaper. The position of the read out on reference to -'3 60 scale willyield the desined direction angle information. The paper 36 is moved .ason nolls by the operator at |a selected speed.

There is shown in FIG. 4 (a count and print out system for recordingdirection tangles. As shown, the direction angle timing pulse from ANDgrate 26 is used to open gate 4t) which is closed by a reference pulsefrom the canrier oscillator 10. Counter 42 driven by clock i4 iscontrolled by gate 4t) :and counts during the period the gate is open.The count during this period is used to activate a corresponding numberof light cells in light box `416 disposed over pblotos'ensitive paper48, the number of yactivated light cells illuminating the photosensitivepaper being proportional to the direction angle. The reference pulse maybe used as shown to reset the counter or the Iactivated lights may bereset 'at the end of each period of carrier oscillation.

The rate of the master clock may be determined by the followingconsidenation:

Let A stand for the smallest incremental direction angle to be displayedon the paper. Then -Oxfo :fm where -frequency of carrier oscillator.fm=frequency of master clock.

The series of lights in box 46 may be replaced by a `series of needles,one of which would be energized by the counter according to directionangle. Special paper, which is shown, would then replace thephotosensitive paper. See FG. 5.

Referring again to lFIG. 4, it is possible in operation to preset thecounter raccordi-ng to la particular direction angle and then feed -asecond direction angle, which may not occur simultaneously, to thereconding system and the resulting display would be the differencebetween the two direction :angles nather than an absolute directionangle. Time between two successive direction angles may be determined bymeasuring the distance between them on paper `and dividing thatdist-ance by the rate of paper tnavel.

Assume that the tactical land geographical situation shown in FIGURE 6exists. A directional listening passive 'sonfar Ineceiver is placed inthe ocean. The characteristic of this receiver is that it isomnidirectionally alert to 4all :signals land gives las 1an output(after processing), X and Y voltages related t-o the signal directionwith respect to a reference bearing of the sonar device.

The target approaches the location of the receiver from the upper right,passing to the lower left. For purposes of :simplification the receiveris assumed to be stationary. Bearing lines :are shown for equaldistances along the target track land these, for a constant targetspeed, are lequal time intervals. The location of an explosive charge is:also shown but is to be disregarded for the time being.

The resulting target plot that would be seen is shown in FGURE 7.Numbens Ialong the left-hand side correspond to the numbered bearinglines of -FiGUR-E 6. The noisy target appnoaches into the listeningrange where the signal is `perceptable labove the random ocean noise iat:about the :location of bearing 1. The angle, with respect to reference,is approximately 20 and is so recorded iat that time. As the targetpasses by the receiver, the bearing changes as the target passes closeby the receiver, bearings `3, `4 and 5, the bearing angle shifts napidlynially passing out of range of the receiver at anourid bearin g 7 wherethe merk passes below the perceptable level of the local ambient noise.At this time the bearing has become essentially constant atapproximately 225.

For the next example, shown in `FIGURE 8 it is assumed that the tar etis running silently and that the signal level never rises lappreciably(above the local ambient noise. The reoonder, thereore, will notreproduce the track of the target as shown in FIGURE 7. Assuming that itis known that the target is in the vicinity, the tactical operationwould be to place a charge bouy somewhere in the water close by thereceiver. This is shown in FIGURE 8 as previously mentioned. A chargebuoy contains sevenal explosive charges that `are released and explodedeither periodically or on command. We will .assume that they laire tiredoff periodically, for simplicity.

The first charge is exploded `and the sound of the explosion islreceived from la relative bearing o-f At a later time, equal to thediierence in the length of the sound paths, the target echo is receivedand seconded along la bearing of approximately 20. The explosive signalsand the subsequent target echo signals are recorded periodically las thecharges are exploded.

-It is not pnactical to keep the 'sonar device xed with repect to theorth Pole. Therefore, |a compass is inserted in the sonar device whichmeasures the angle between .son'afr device and the North Pole. Thedifference between the compass angle yand the bearing :angle from sonardevice in the true bearing of target with respect t0 the 'North Pole. Itis this difference angle which is of tactical interest.

Various modifications of this invention may be effected by personsskilled in the art without departing from the scope yand principle ofthe invention :as defined by the claims. -1

What is claimed is:

l. Means for recording direction angle signals of a transient naturecomprising -a carrier oscillator, a display device synchronized withsaid oscillator, a phase shifter connected to said oscillator, amodulator connected to the output of said phase shifter, la secondmodulator connected to said oscillator, la summing 'amplifier connectedto the output of both modulators, means connected to said amplifier fordetecting a preselected relative output value thereof and generating lapulse each time said value is detected, said Idisplay ydevice bei-ngactuated by said generated pulse, said detecting and generating meanscomprising la 90 phase shifter land :a zero crossing detector connectedto the output lof `said 90 phase shifter, an AND gate connected to theoutput of said Zero cnossing detector rand :a signal threshold triggeris connested between said Isumming `amplifier :and said AND gate.

2. Means for @recording direction .angle signals of a transientinlatuine comprising a camrieir oscillator, a display devicesynchronized with said oscillator, a phase shifter connected to saidoscillator, a modulator connected to the output of said phase shifter, aseco-nid modulator connected to said oscillator, la :summing 'amplifierconnected to the output of both modulators, means connected to saidamplier for detecting 'a preselected relative output value thereof andgenerating Ia. pulse yeach time said value is detected, said :displaydevice being actuated by s'aid generated pulse, Islaid display devicebeing a dual beam linear sweep lolscillfoecope, lan event `signal linebeing co11- nected to fsaird oscilloscope, la time 'sweep line beingalso connected thereto and having a threshold detector and linear timesweep genenatiolr disposed the-rein :and connected to receive the outputof said means for detecting a pre-.selected output velue.

References Cited by the Examiner UNITED STATES PATENTS 2,754,493 7/1956Lippel 340-16 3,027,219 .v3/1962 Bmdley 346-110 3,091,762 5/1963Schwartz 343-11 3,148,351 9/1964 Bartlett 340-16 3,180,977 4/1965 13mm23S-189 3,187,169 6/1965 Trammell etai. 23S-189 OTHER REFERENCES Waynicket tal.: A `Polar Vector Indicator, National Electronics ConferenceProc., vol. 4, published Feb. 28, 1949, pp. 279 and 282 irelied on.

yRODNEY, D. BENNETT, Primary Examiner. LEWIS H. MYERS, CHESTER L.JUSTUS, Examiners.

R. A. FARLEY, Assistant Examiner.

1. MEANS FOR RECORDING DIRECTION ANGLE SIGNALS OF A TRANSIENT NATURECOMPRISING A CARRIER OSCILLATOR, A DISPLAY DEVICE SYNCHRONIZED WITH SAIDOSCILLATOR, A PHASE SHIFTER CONNECTED TO SAID OSCILLATOR, A MODULATORCONNECTED TO THE OUTPUT OF SAID PHASE SHIFTER, A SECOND MODULATORCONNECTED TO SAID OSCILLATOR, A SUMMING AMPLIFIER CONNECTED TO THEOUTPUT OF BOTH MODULATORS, MEANS CONNECTED TO SAID AMPLIFIER FORDETECTING A PRE-SELECTED RELATIVE OUTPUT VALUE THEREOF AND GENERATING APULSE EACH TIME SAID VALUE IS DETECTED, SAID DISPLAY DEVICE BEINGACTUATED BY SAID GENERATED PULSE, SAID DETECTING AND GENERATING MEANSCOMPRISING A 90* PHASE SHIFTER AND ZERO CROSSING DETECTOR CONNECTED TOTHE OUTPUT OF SAID 90* PHASE SHIFTER AN "AND" GATE CONNECTED TO THEOUTPUT OF SAID ZERO CROSSING DETECTOR AND A SIGNAL THRESHOLD TRIGGER ISCONNECTED BETWEEN SAID SUMMING AMPLIFIER AND SAID "AND" GATE.